ALBERT

Description: Hillslopes are one of the basic units that mainly control water movement and flow pathways within catchments. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap of knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. To improve the knowledge of hydrological responses on hillslopes with periglacial cover beds, hydrometrical measurements have been carried out on a small spring catchment in the eastern Ore Mountains since November 2007. In addition, surface ERT measurements of several profiles were applied to enhance resolution of punctual hydrometric data. From May to December 2008 geoelectrical monitoring in nearly weekly intervals was implemented to trace seasonal moisture dynamics on the hillslope scale. To obtain the link between water content and resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data and resulting in remarkable coincidence. The measured resistivity shows a close correlation with precipitation. Depending on the amount and intensity of rain, different depths were affected by seepage water. Three different types of response to different amounts of precipitation (small, medium, high), could be differentiated. A period with a small amount causes a short interruption of the drying pattern at the surface in summer, whereas a medium amount induces a distinctive reaction at shallow depth (

Description: Besides floodplains, hillslopes are basic units that mainly control water movement and flow pathways within catchments of subdued mountain ranges. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap in the knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. This study presents a robust multi-method framework of electrical resistivity tomography (ERT) in addition to hydrometric point measurements, transferring hydrometric data into higher spatial scales to obtain additional patterns of distribution and dynamics of soil moisture on a hillslope. A geoelectrical monitoring in a small catchment in the eastern Ore Mountains was carried out at weekly intervals from May to December 2008 to image seasonal moisture dynamics on the hillslope scale. To link water content and electrical resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data. The results from ERT measurements show a strong correlation with the hydrometric data. The response is congruent to the soil tension data. Water content calculated from the ERT profile shows similar variations as that of water content from soil moisture sensors. Consequently, soil moisture dynamics on the hillslope scale may be determined not only by expensive invasive punctual hydrometric measurements, but also by minimally invasive time-lapse ERT, provided that pedo-/petrophysical relationships are known. Since ERT integrates larger spatial scales, a combination with hydrometric point measurements improves the understanding of the ongoing hydrological processes and better suits identification of heterogeneities.